Full stroke compelling mechanism



Sept 8, 19170 v, P. Dl FILIPPO 3,527l,l25

FULL STROKE COMPELLING MECHANISM Filed Feb. '7, 1968 United StatesPatent O U.S. Cl. Sil-i113 6 Claims ABSTRACT OF THE DISCLOSURE Amechanism for insuring proper jaw closure in a tool having a pair ofhandles which are linked to each other and to the jaws. The mechanismincludes a pawl having a pawl housing which is pivotally connected to apair of links. Each handle is pivotally connected to the other end ofeach link. A ratchet housing and guide means is provided which houses aratchet and which guides the pawl rectilinearly along the ratchet uponclosure of the handles. The pawl and ratchet mechanism prevents openingof the handles and, therefore, the jaws prior to the attainment of apredetermined force applying position of the jaws.

BACKGROUND OF THE INVENTION Various types of hand tools are in use todaywhich are provided with two or more force applying dies which are movedtogether to apply their force to a workpiece. For example, hand toolshave been provided which have crimping dies for crimping one portion ofa ferrule directly upon an electrical conductor. Such hand crimpingtools include various types of full stroke compelling mechanisms toinsure a completed crimping operation prior to opening of the jaws. Onesuch tool is set forth in Carlson Pat. No. 2,618,993. The Carlson patentrelates to a plier like hand tool having a full stroke compellingmechanism which includes a pawl and ratchet assembly. The pawl andratchet assembly is contained in a link which is pivoted at one end toan upper portion of one of the handles and which is pivoted at its otherend to a lower portion of the other handle. Upon closure of the handles,the link is telescopically collapsed until the pawl overrides theratchet and is telescopically extended upon opening the handles.

Other prior art full stroke compelling mechanisms are similar to themotion compelling mechanism set forth in Filia Pat. No. 3,157,075. TheFilia patent has a ratchet which is adjustably connected to one of thehandles of a plier like crimping tool and has a cooperating pawlpivotally connected to the other handle so that, upon closure of thehandles, the pawl overrides the ratchet to prevent reversal of thehandles prior to the desired jaw closure. In the Filia patent the pawland ratchet mechanism is located relatively close to the pivotalconnection between the handles.

Although these prior art full stroke compelling assemblies perform theirintended functions, they have certain disadvantages. The provision ofpawl and ratchet housing which comprises a link extending from an upperportion of one of the handles to a lower portion of the other handle,such as shown in Carlson Pat. No. 2,618,993, results in a tool having anelement between the handles which may tend to pinch the operators handwhen the handles are closed. Moreover, if an object is trapped betweenthe pawl and ratchet housing and one of the handles during closure ofthe Carlson tool, it may be impossible to remove such an object untilthe pawl overruns the ratchet, thereby causing the application offurther pressure on the object by the ratchet housing.

ICC

Although this problem is not as acute in the device shown in the Filiapatent, the location of the pawl and ratchet mechanism close to thepivot point between the handles results in a relatively large reactionforce on the pawl and ratchet if the handles are released prior to thetime when the pawl overruns the ratchet. This reaction force istransmitted by the workpiece being crimped since that piece tends tospring back to an uncrimped condition and, since the pawl and ratchetwill not permit reversal of the handles prior to the time when the pawloverruns the ratchet, the reaction force of the partially crimpedworkpiece applies considerable force to the point of engagement betweenthe pawl and ratchet.

Prior art hand tools having a pawl and ratchet assembly to insure a fullstroke must be returned to the manufacturer in order to replace wornratchets, since those ratchets are pivotally connected to a portion ofthe tool. The expense involved in returning those tools and in replacingthe ratchet assembly usually induced the user to buy a new tool.

SUMMARY OF THE INVENTION According to this invention a force applyinghand tool is provided which overcomes these prior art problems. The toolincludes a mechanism for insuring a full stroke and for insuring theattainment of a desired force applying position by the jaws of the tool.The full stroke insuring means according to this invention includes apawl which is linked to at least one of the handles of the tool andincludes a ratchet which is mounted on a guide member. The guide memberguides the pawl in a straight line toward the jaw end of the tool duringclosure of the handles so that the pawl engages the ratchet during suchmovement and cannot be moved in the reverse direction until the jawshave attained a desired force applying position. The ratchet maycomprise a threaded cylindrical member which may be adjusted so that thedesired force applying position (the point at which the pawl leaves thelast tooth of the ratchet) may be adjusted. The ratchet may easily bereplaced by unscrewing it from the guide means and without thedisassembly of the tool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, withportions broken away for clarity, of a hand tool having a full strokeinsuring mechanism according to this invention.

FIG. 2 is an enlarged, fragmentary view, with certain portions brokenaway for clarity, of the full stroke insuring mechanism.

FIG. 3 is a cross-sectional view, the plane of the section beingindicated by the line 3--3 in FIG. 2.

FIG. 4 is a cross-sectional view, the plane of the section beingindicated by the line 4-4 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION A crimping tool 10 comprises apair of levers 11 and 12 having a U-shaped cross section. The levers 11and 12 are pivotally connected at a pivot point 13 and are spring biasedin a normally separated condition by a spring 14. In the drawings thehandles 11 and 12 of the tool 10 are illustrated in a closed position.The levers 11 and 12 are pivoted at their upper ends to a pair of jawplates .15 and 16, respectively, by a pair of pins 17 and 18.

The jaw plates 15 and 16 are pivoted for relative rocking movement abouta rocking pin 19 and are connected to each other by pivot pins 20 and 21which extend through the jaw plates 15 and 16 and by two straps 22. Whenthe levers 11 and 12 are moved toward each other,

the jaw plates and 16 are pivoted about the pivot points and 2.1 androck about the rocking pin 19 to assume the position shown in FIG. 1.

The jaw plates 15 and 16 are provided with opposed ferrule forming dieportions and 26, respectively, which may be designed to provide anydesired crimp to a ferrule when the jaws are actuated by the levers 11and 12. The die portions 25 and 26 may be designed to crimp the ferruleportion of a terminal or connector directly onto a conductor to providea solderless electrical connection.

The levers 11 and 12 have an adjustable locking, full stroke compellingor insuring mechanism associated therewith. As is shown, this mechanismcomprises a pawl 27 and a ratchet 28. The pawl 27 is pivotally mountedon a pin 29 and is normally held in the position illustrated in FIGS. 2and 4 by a tension spring 30. The spring 30 is connected at one end to apin 31 which extends through a reduced end portion 32 of the pawl 27 andis connected at its other end to a pin 33 which is press tted into apawl housing 34.

The pawl housing is mounted for rectilinear movement within a guidehousing 35. The guide housing 35 has parallel face plates 36 and 37which are joined by a web portion 38. The pin 29 to which the pawl 27 ispivotally connected extends outwardly beyond the pawl housing 34 andinto slots 39 and 40 which are respectively provided in the plates 36and 37. A pin 41 extends through the other end of the housing 34 andextends into each slot 39 and 40 so that the pawl housing 34 may beguided rectilinearly in the guide housing 35.

The web portion 37 is provided with a longitudinal bore which isthreaded to receive the ratchet 28. The ratchet 28 comprises a threadedpin having a slotted end portion 42. Prior to the installation of theratchet 28, a portion of the web 38 is ground away so that a portion ofthe threaded surface of the ratchet 28 is exposed to a tooth 43 on thepawl 27. The guide housing 35 is pivotally connected to the pin .13 sothat the slots 39 and 40 have axes which intersect the center of thepivot pin 13.

The pawl housing is rectilinearly driven within the guide housing 35 bylinks 44 and 45. One end of the link 44 is pivoted to the lever 11 by apin 46 and one end of the line 45 is pivoted to the lever 12 by a pin47. The pins 46 and 47 are located equidistant from the pivot pin 13.The other end of each line 44 and 45 is pivotally connected to the pin41.

Upon closure of the levers 11 and 12, the links 44 and 45 drive the pawlhousing 44 toward the pivot pin 13. As the pawl housing 34 is driven inthis manner, the pawl 27 is turned in a clockwise direction from theposition illustrated in FIG. 2 so that the pawl tooth 43 rides alongeach tooth on the ratchet 28. During this movement, the levers 11 and 12may not be opened since the position of the pawl cannot be reverseduntil the pawl tooth 43 leaves the last ratchet tooth to permit the pawlto return to the position illustrated in FIG. 2. When the pawl tooth 43has overrun the last ratchet tooth in this fashion, the levers 11 may beopened by the spring 14 since the pawl may travel over the ratchet 28and away from the pivot pin 13 by being rotated in a counterclockwisedirection upon engagement of the ratchet.

Since the last ratchet tooth must be traversed in order to permit thelever 11 and 12 (and therefore the jaw plates 15 and 16) to open, theposition of the last ratchet tooth determines a desired force applyingposition of the jaws. The position of the last tooth may be varied byinserting a screw driver between the plates 36 and 37 and into the notch42 and by turning the ratchet 28 within the web 38. Such an adjustmentmay be made by moving the levers 11 and 12 together until the jawsestablish a desired force applying position. Such a force applyingposition may be established without actual jaw contact by inserting ashim between the jaws, closing the jaws on the shim, and by unscrewingthe ratchet 28 until the pawl tooth 43 leaves the last ratchet tooth.Such a force applying position may be established with the jaws closedand in contact with each other by closing the levers 11 and 12 until thejaws touch and by unscrewing the ratchet 28 until the pawl tooth 43leaves the last ratchet tooth. This adjustment may be effected with thehandles flexed together after jaw contact so that in a crimpingoperation the pawl tooth 43 will not leave the last ratchet tooth untilafter there is jaw contact and handle flexure.

The invention is not restricted to the slavish imitation of each andevery detail set forth above. Obviously, devices may be provided Whichchange, add, or eliminate certain details without departing from thescope of the invention.

What is claimed is:

1. In a tool having force applying jaws which are moved together to adesired force applying position by closing a pair of pivotally connectedhandles, the irnprovement comprising full stroke insuring means toprevent opening of the jaws prior to the attainment of said desiredforce applying position, said full stroke insuring means including apawl member and a ratchet member, rst linkage means linking one of saidmembers to at least one of said handles, second linkage means attachedto a pivotal connection between the handles, the other of said membersbeing fixed to said second linkage means, said second linkage meanshaving means for guiding said one of said members in a straight linetoward said pivotal connection and in ratcheting relationship relativeto the member fixed to said second linkage means during closure of thehandles.

2. The improvement according to claim 1 wherein said other of saidmembers is adjustable relative to said second linkage means.

3. The improvement according to claim 1 wherein said one of said memberscomprises the pawl member and wherein said other of said memberscomprises the ratchet member.

4. The improvement according to claim 1 wherein said rst linkage meanscomprises a pair of links, each of said links having one end pivotallyconnected to its own one of said handles at pivotal connections whichare equidistant from the pivotal connection between the handles.

5. In a tool having force applying jaws which are moved together to adesired force applying position by closing a pair of handles which arelinked to the jaws and to each other, the improvement comprising fullstroke insuring means to prevent opening of said jaws prior to theattainment of said desired force applying position, said full strokeinsuring means including a pawl member and a ratchet member, linkagemeans comprising a pair of links, each link being pivotally connected atone end to its own one of said handles, the other end of each link beingpivotally connected to said pawl, a ratchet housing, said ratchethousing having said ratchet mounted thereon and including guide meansfor guiding the pawl in a straight line toward said jaws and inratcheting relationship relative to the ratchet during closure of thehandles.

6. In a tool having force applying jaws which are moved together to adesired force applying position by closing a pair of handles which arelinked to the jaws and pivotally connected to each other, theimprovement comprising full stroke insuring means to prevent the openingof the jaws prior to the attainment of said desired force applyingposition, said full stroke insuring means including a pawl member and aratchet member, a pair of links each of said pair of links having oneend pivotally connected to its own one of said handles, the other end ofeach of said pair of links having said pawl pivotally connected thereto,a ratchet housing pivotally connected to the pivotal connection betweenthe handles, said ratchet housing comprising a pair of plates connectedby a web portion, guide means in each plate cooperating with said pawlfor guiding said pawl in a straight line toward said pivot point, saidratchet comprising a threaded cylinder 5 6 partially mounted in said webportion and having teeth 2,737,070 3/ 1956 Dibner 74-175 X cooperatingwith said pawl in ratcheting relationship with 2,737,071 3/ 1956 Dibner74-17.5 X

said pawl during closure of the handles.

ROBERT C. RIORDON, Primary Examiner References Cited 5 R. V. PARKER,JR., Assistant Examiner UNITED STATES PATENTS 953,507 3/1910 Beales1-3i3 X U-S- Cl- X-R 2,618,993 11/1952 Carlson 81-313X 72-409

